Linkage assembly preventing axial rotation of the link rod for a gas turbine engine

ABSTRACT

Disclosed is a linkage assembly for a gas turbine engine having a link having a first end, a second end, and a rod extending therebetween, the first end having a first sliding bearing disposed within a first sliding bearing housing, a fastener comprising a first flange and a second flange, a pin extending between the first flange and the second flange, wherein the first sliding bearing is pivotally connected to the pin; and a biasing member secured between the first flange and the sliding bearing housing, the biasing member contacting the sliding bearing housing and biasing the link against rotation about a center axis for the rod of the link.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/700,042 filed Sep. 8, 2017, the disclosure of which is incorporatedherein by reference in its entirety

STATEMENT OF FEDERAL SUPPORT

This invention was made with Government support under Contract No.FA8626-15-D-0015-3501/3502 awarded by the United States Air Force. TheGovernment has certain rights in the invention.

BACKGROUND

Exemplary embodiments pertain to the art of connection joints and morespecifically to linkage assemblies in gas turbine engines that includelinks, which convert rotation to linear motion.

An implementation of a radial spherical plain bearing link (link) allowsfor three rotational degrees of freedom at each end of the link. In alinkage assembly where the link is intended to convert rotational motionto linear motion this configuration may result in an unconstrainedrotational degree of freedom about a longitudinal axis of the link. Asolution is desired to remove the rotational degree of freedom that canbe applied to current and future implementations preferably without theneed to replace hardware.

BRIEF DESCRIPTION

Disclosed is a linkage assembly for a gas turbine engine comprising: alink having a first end, a second end, and a rod extending therebetween,the first end having a first sliding bearing disposed within a firstsliding bearing housing, a fastener comprising a first flange and asecond flange, a pin extending between the first flange and the secondflange, wherein the first sliding bearing is pivotally connected to thepin; and a biasing member secured between the first flange and thesliding bearing housing, the biasing member contacting the slidingbearing housing and biasing the link against rotation about a centeraxis for the rod of the link.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the first flange has afirst elongated C-groove and the second flange has a second elongatedC-groove, each elongated C-groove opening towards the first slidingbearing housing, and the biasing member comprises a plurality of biasingmembers, including: a first elongated C-brace seated in the firstelongated C-groove and contacting the first sliding bearing housing, anda second elongated C-brace seated in the second elongated C-groove andcontacting the first sliding bearing housing.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the first elongatedC-brace has a first opening and the second elongated C-brace has asecond opening and the pin extends through the first elongated C-braceopening and the second elongated C-brace opening.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the first elongatedC-brace has a first set of circumferential ends disposed against thefirst sliding bearing housing and the second elongated C-brace has asecond set of circumferential ends disposed against the first slidingbearing housing.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the biasing member isan elastic biasing member that includes a first annular spacer having afirst opening through which the pin extends, the first annular spacercontacting the first flange and the first sliding bearing.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the biasing member isa flat U shaped spring having a first leg extending along the firstflange, a second leg extending away from the first sliding bearinghousing, a return bend, and a return leg extending toward the firstsliding bearing housing to press against the first sliding bearinghousing.

In addition to one or more of the features described above, or as analternative, further embodiments may include a second annular spacerhaving a second opening through which the pin extends, the secondannular spacer disposed between the second flange and the first slidingbearing.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the first annularspacer and second annular spacer are contoured to fit against an arcuatesurface of the first sliding bearing.

Further disclosed is a gas turbine engine including: an engine fixedstructure; and a plurality of linkage assemblies connecting the enginefixed structure to the movable engine structure, each linkage assemblycomprising one or more of the above disclosed features.

In addition to one or more of the features described above, or as analternative, further embodiments may include a variable area exhaustnozzle, wherein: a flap train of the variable area exhaust nozzle is theengine movable structure and a synchronization ring for the variablearea exhaust nozzle is slidingly disposed in the engine fixed structure,and each fastener is a bell crank having three pivotal connectionpoints, including a first pivotal connection point connected to thefirst sliding bearing, a second pivotal connection point that is afulcrum connected to the engine fixed structure, and a third pivotalconnection point connected to a coupler link, the coupler linkconnecting each fastener to the synchronization ring.

In addition to one or more of the features described above, or as analternative, further embodiments may include that for each linkageassembly, the second end of the link includes a second sliding bearingin a second sliding bearing housing, and the second sliding bearing ispivotally connected to the flap train.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the synchronizationring is slidingly disposed in a linearly extending cavity in the enginefixed structure.

In addition to one or more of the features described above, or as analternative, further embodiments may include that the flap trainincludes a plurality of flap train links pivotally connected between theflap train and the engine fixed structure for controlling pivotal motionof the flap train.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 is an exploded view of a gas turbine engine according to anembodiment of the disclosure;

FIGS. 2A, 2B and 2C illustrate a portion of a variable area exit nozzleconnected to a plurality of linkage assemblies according to anembodiment of the disclosure;

FIG. 3 is a link according to an embodiment of the disclosure;

FIG. 4 is a linkage assembly according to an embodiment of thedisclosure;

FIGS. 5A-5D illustrate features of a linkage assembly according to anembodiment of the disclosure;

FIG. 6 is brace for a linkage assembly according to an embodiment of thedisclosure;

FIG. 7 illustrates a linkage assembly according to an embodiment of thedisclosure;

FIG. 8 illustrates a spacer for a linkage assembly according to anembodiment of the disclosure; and

FIGS. 9a-9b illustrate a biasing member for a linkage assembly accordingto an embodiment of the disclosure.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures.

FIG. 1 schematically illustrates a gas turbine engine 20. The gasturbine engine 20 is disclosed herein as a two-spool turbofan thatgenerally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mightinclude an augmentor section (not shown) among other systems orfeatures. The fan section 22 drives air along a bypass flow path B in abypass duct, while the compressor section 24 drives air along a coreflow path C for compression and communication into the combustor section26 then expansion through the turbine section 28. Although depicted as atwo-spool turbofan gas turbine engine in the disclosed non-limitingembodiment, it should be understood that the concepts described hereinare not limited to use with two-spool turbofans as the teachings may beapplied to other types of turbine engines including three-spoolarchitectures.

The exemplary engine 20 generally includes a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A relative to an engine static structure 36 viaseveral bearing systems 38. It should be understood that various bearingsystems 38 at various locations may alternatively or additionally beutilized, and the location of bearing systems 38 may be varied asappropriate to the application.

The low speed spool 30 generally includes an inner shaft 40 thatinterconnects a fan 42, a low pressure compressor 44 and a low pressureturbine 46. The inner shaft 40 is connected to the fan 42 through aspeed change mechanism, which in exemplary gas turbine engine 20 isillustrated as a geared architecture 48 to drive the fan 42 at a lowerspeed than the low speed spool 30. The high speed spool 32 includes anouter shaft 50 that interconnects a high pressure compressor 52 and highpressure turbine 54. A combustor 56 is arranged in exemplary gas turbine20 between the high pressure compressor 52 and the high pressure turbine54. An engine static structure 36 is arranged generally between the highpressure turbine 54 and the low pressure turbine 46. The engine staticstructure 36 further supports bearing systems 38 in the turbine section28. The inner shaft 40 and the outer shaft 50 are concentric and rotatevia bearing systems 38 about the engine central longitudinal axis A,which is collinear with their longitudinal axes.

The core airflow is compressed by the low pressure compressor 44 thenthe high pressure compressor 52, mixed and burned with fuel in thecombustor 56, then expanded over the high pressure turbine 54 and lowpressure turbine 46. The turbines 46, 54 rotationally drive therespective low speed spool 30 and high speed spool 32 in response to theexpansion. It will be appreciated that each of the positions of the fansection 22, compressor section 24, combustor section 26, turbine section28, and fan drive gear system 48 may be varied. For example, gear system48 may be located aft of combustor section 26 or even aft of turbinesection 28, and fan section 22 may be positioned forward or aft of thelocation of gear system 48.

The engine 20 in one example is a high-bypass geared aircraft engine. Ina further example, the engine 20 bypass ratio is greater than about six(6), with an example embodiment being greater than about ten (10). Inone disclosed embodiment, the engine 20 bypass ratio is greater thanabout ten (10:1), the fan diameter is significantly larger than that ofthe low pressure compressor 44, and the low pressure turbine 46 has apressure ratio that is greater than about five 5:1. Low pressure turbine46 pressure ratio is pressure measured prior to inlet of low pressureturbine 46 as related to the pressure at the outlet of the low pressureturbine 46 prior to an exhaust nozzle. It should be understood, however,that the above parameters are only exemplary of one embodiment of ageared architecture engine and that the present disclosure is applicableto other gas turbine engines including direct drive turbofans.

Turning to FIGS. 1, 2A-2C, and 3, portions of a variable area exhaustnozzle (nozzle) 70 are illustrated. In addition, a plurality of bearinglinkages (or links) 102 a-102 d including first link 102 a areillustrated. The links 102 a-102 d may be radial spherical plain bearinglink rods. The links 102 a-102 d may be indirectly connected on one sideto a synchronization (or synch) ring 80 for example, as positioned by anactuator or other device (not shown) for prescribing the axial positionof the sync ring 80. The synch ring 80 may translate in an engine fixedstructure 82. The synch ring 80 may slidingly drive the link assembly inthe disclosed embodiment.

The synch ring 80 may be pivotally connected to a coupler rod (or link)84. The coupler link 84 may in turn may be pivotally connected to aL-link (or bell crank) 86. The fulcrum 88 of the bell crank 86 may bepivotally connected to the engine fixed structure 82 and the bell crank86 may convert linear motion from the synch ring 80 to rotationalmotion.

As illustrated in FIGS. 2A, 2B and 2C, the rotational motion from thebell crank 86 may be transferred to the links 102 a-102 d. Each of thelinks 102 a-102 b may be pivotally connected on opposing longitudinalend joints 104 a, 104 b of the respective links 102 a-102 b between thebell crank 86 and a movable flap train 91. This connection transfersrotational motion to plural flap train links including a first flaptrain link 89 and a second flap train link 90 controlling motion of theflap train 91. The flap train links 89, 90 may be respectively pivotallyconnected to the flap train 91 at locations upstream 93 and downstream95 of the end joint 104 b of the respective links 102 a-102 d. Onopposing longitudinal ends 97, 99 of the flap train links 89, 91 may bepivotally connected to the engine fixed structure 82. The links 102a-102 d function as drive links and the movable flap train 91 moves inresponse to the synch ring 80 to change the area of the nozzle. It is tobe appreciated that such links 102 a-102 d may be also used for otheraircraft moving parts, such as variable vanes and landing gear.

Turning to FIGS. 3 and 4, further attention will be given to thestructure of the first link 102 a and a connection of the same to thebell crank 86. The first link 102 a may have first and second heads (orjoint ends) 104 a, 104 b that may be connected by a tubular rod 106.Turning to the first joint end 104 a, a sliding bearing 108 isillustrated in a bearing housing 107. The sliding bearing 108 has anarcuate contact surface and may be a radial spherical plain bearing.

The bearing housing 107 has first and second opposed planar surfaces 110a, 110 b and a profile shape that may define a teardrop shape or afisheye or a lollypop shape. The sliding bearing 108 may include acenter bore 114 and a cylindrical collar 116 may extend outwardly fromthe bore 114. Though the discussion herein includes the collar 116 anembodiment without the collar 116 is within the scope of the disclosure.

The first link 102 a may be pivotally connected to the bell crank 86 viaa clevis fastener (or fastener) 118. The bracket 118 may have first andsecond opposed flanges 126 a, 126 b and a pin 120 extendingtherebetween. The pin 120 may have a diameter sized to slide throughbore 114 of the sliding bearing 108. Each of the flanges 126 a, 126 bmay have a center opening 128 a, 128 b for the pin 120 to slidetherethrough. The span between the flanges 126 a, 126 b may be smallenough so that the sliding bearing 108 does not slide therebetween. Withthis configuration the first link 102 a may rotate about the slidingbearing 108 while the sliding bearing 108 remains stationary on thebracket 118.

A pin free end 125 may be locked against an external side of the firstflange 126 a with a pin lock 132. The pin head 124 may contact anexterior of the second flange 126 b.

Turning to FIGS. 5A-5D and 6, first and second biasing members, whichmay be elongated C-braces 136 a, 136 b, may be included. FIGS. 5A-5Cillustrate various details disclosed below for modifying the fastener118 and assembling the C-braces 136 a, 136 b thereon. FIG. 6 illustratesthe first C-brace 136 a in isolation.

The C-braces 136 a, 136 b bias the first link 102 a against rotationabout the rod center axis i.e., against the direction 150 illustrated inFIG. 3. The C-braces 136 a, 136 b may be rigid, i.e., inelastic, toprevent rotation about the rod center axis. The first C-brace 136 a maybe positioned between the bearing housing 107 and the first flange 126a. The second C-brace 136 b may be positioned between the bearinghousing 107 and the second flange 126 b.

Turning to the first C-brace 136 a, a first through-hole (or opening)144 may be disposed therein. The first C-brace opening 144 has adiameter sized to slide over the pin 120 and collar 116, as illustratedin FIG. 5C. An inner facing surface (e.g., facing a center of thebracket 118) of the first C-brace 136 a may have a diameter sized to fitagainst the sliding bearing 108. A first inner facing arcuate cutout (orelongated C-groove) 146 a may be disposed in the inner facing surface134 a of the first flange 126 a as illustrated in FIGS. 5B-5D. TheC-grove 146 a extends in the same direction as the length of the firstC-brace 136 a, e.g., in the direction defined between the top edge 137and bottom edge 139 of the first C-brace 136 a. The C-grove 146 a seatsan outer facing surface (e.g., facing away from a center of the bracket118) of the first C-brace 136 a as illustrated in FIGS. 5C and 5D. Asecond C-grove 146 b on the second inner facing surface 134 b of thesecond flange 126 b is illustrated with the second C-brace 136 b in FIG.5D.

With both C-braces 136 a, 136 b in the linkage assembly, a first set ofopposing circumferential ends 140 a, 142 a of the first C-brace 136 acontacts the first housing surface 110 a. Concurrently a second set ofopposing circumferential ends 140 b, 142 b of the second C-brace 136 bcontacts the second housing surface 110 b. The C-braces 136 a, 136 b arelong enough to disburse reactance forces and torques into the C-bracesand bearing housing without damaging the same. As such, the wearsurfaces for the linkage assembly are the housing surfaces 110 a, 110 band the sets of opposing circumferential ends of the C-braces 136 a, 136b.

Turning to FIG. 7, another embodiment is disclosed where the rod 106 ofthe link 102 a has a longitudinal axis (RA) that may be offset oracutely angled away from the first flange 126 a and toward the secondflange 126 b. In such circumstance, the biasing member may be an elasticbiasing member such as a spring 200 that eliminates rotational motion inthe direction 150 illustrated in FIG. 3. As illustrated the spring 200may be disposed between the first flange 126 a and the first housingsurface 110 a.

A first washer 202 may be disposed against the second flange 126 b forcentering the sliding bearing 108 on the bracket 118. As illustrated inFIGS. 7 and 8, the first washer 202 may have an orifice 204 with achamfered edge 206. This configuration enables the first washer 202 tofit around the collar 116 and against the sliding bearing 108 to causesliding contact, i.e., a wear surface. The outer diameter 208 of thefirst washer 202 is illustrated as being substantially the same as thespherical diameter of the sliding bearing 108, though other diametersare within the scope of the disclosure.

With reference to FIGS. 7, 8, 9 a and 9 b, the spring 200 also has asecond washer (a spring washer) 210, which may be sized similarly to thefirst washer 202. The spring washer 210 is an additional wear surfaceand centers the bearing housing 107 between the flanges 126 a, 126 b.

The spring 200 forms a U-shaped compression spring having a linearlyextending first leg 212 that extends away from the spring washer 210 andextends adjacent to the first flange 126 a. At the end of the first leg212, there is a bend (or inflection) 222 in the spring 200 after which asecond leg 213 continues to extend away from the spring washer 210 andis angled away from the bearing housing 107. Such bend may result in aspring configuration having additional spring pre-loading and/or springpotential.

At the end of the second leg 213 the spring 200 has a return U-bend 214and a linearly extending return leg 215 that extends back toward thespring washer 210 and is angled toward the bearing housing 107. A springfoot (or free end) 216 contacts the first housing surface 110 a andextends partially back toward the first flange 126 a. This configurationresults in an edgeless contact at the location of expected surface wear.The depth-wise span of the spring 200 enables contact between the freeend 216 of the spring 200 and the first housing surface 110 a throughoutthe rotational range of the first link 102 a.

As illustrated in FIG. 9B, the side profile edges 218, 220 of the spring200 may extend tangentially between the spring washer 210 and the returnbend 214. The resulting shape in a plan view is a rounded trapezoid.

It is to be appreciated that a configuration in which an additionalspring is between the second flange 126 b and the bearing housing 107 iswithin the scope of the disclosure.

The term “about” is intended to include the degree of error associatedwith measurement of the particular quantity based upon the equipmentavailable at the time of filing the application.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentdisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,element components, and/or groups thereof.

While the present disclosure has been described with reference to anexemplary embodiment or embodiments, it will be understood by thoseskilled in the art that various changes may be made and equivalents maybe substituted for elements thereof without departing from the scope ofthe present disclosure. In addition, many modifications may be made toadapt a particular situation or material to the teachings of the presentdisclosure without departing from the essential scope thereof.Therefore, it is intended that the present disclosure not be limited tothe particular embodiment disclosed as the best mode contemplated forcarrying out this present disclosure, but that the present disclosurewill include all embodiments falling within the scope of the claims.

What is claimed is:
 1. A linkage assembly for a gas turbine enginecomprising: a link having a first end, a second end, and a rod extendingtherebetween, the first end having a first sliding bearing disposedwithin a first sliding bearing housing, the first sliding bearinghousing having first and second opposed planar surfaces, a fastenercomprising a first flange and a second flange that respectively havefirst and second inner facing surfaces, a pin extending between thefirst flange and the second flange, wherein the first sliding bearing ispivotally connected to the pin so that the first planar surface of thesliding bearing housing faces the first inner facing surface of thefirst flange and the second planar surface of the sliding bearinghousing faces the second inner facing surface of the second flange; anda biasing member secured between the first inner facing surface of thefirst flange and the first planar surface of the sliding bearinghousing, the biasing member contacting the first planar surface of thesliding bearing housing and biasing the link against rotation about acenter axis for the rod of the link, and wherein the biasing member isan elastic biasing member that includes a first annular spacer, defininga washer, having a first opening through which the pin extends, thefirst annular spacer contacting the first inner facing surface of thefirst flange and the first planar surface of the first sliding bearing,and wherein the biasing member is a flat U shaped spring having: a firstleg extending along the first inner facing surface of the first flange;a second leg extending away from the first planar surface of the firstsliding bearing housing; a return bend; and a return leg extendingtoward the first planar surface of the first sliding bearing housing,and a foot of the return leg defining a free end of the biasing member,presses against the first planar surface of the first sliding bearinghousing.
 2. The assembly of claim 1, including a second annular spacerhaving a second opening through which the pin extends, the secondannular spacer disposed between the second flange and the first slidingbearing.
 3. The assembly of claim 2, wherein the first annular spacerand second annular spacer are contoured to fit against an arcuatesurface of the first sliding bearing.
 4. A gas turbine engine including:an engine fixed structure; a plurality of linkage assemblies connectingthe engine fixed structure to a movable engine structure, each linkageassembly comprising: a link having a first end, a second end, and a rodextending therebetween, the first end having a first sliding bearingdisposed within a first sliding bearing housing, the first slidingbearing housing having first and second opposed planar surfaces, afastener comprising a first flange and a second flange that respectivelyhave first and second inner facing surfaces, a pin extending between thefirst flange and the second flange, wherein the first sliding bearing ispivotally connected to the pin so that the first planar surface of thesliding bearing housing faces the first inner facing surface of thefirst flange and the second planar surface of the sliding bearinghousing faces the second inner facing surface of the second flange; anda biasing member secured between the first inner facing surface of thefirst flange and the first planar surface of the sliding bearinghousing, the biasing member contacting the first planar surface of thesliding bearing housing and biasing the link against rotation about acenter axis for the rod of the link, and wherein the engine fixedstructure is connected to the linkage assemblies through each fastenerand the engine movable structure is connected to the linkage assembliesthorough each link, and wherein for each linkage assembly: the biasingmember is an elastic biasing member that includes a first annularspacer, defining a washer, having a first opening through which the pinextends, the first annular spacer contacting the first inner facingsurface of the first flange and the first planar surface of the firstsliding bearing, and wherein the biasing member is a flat U shapedspring having: a first leg extending along the first inner facingsurface of the first flange; a second leg extending away from the firstplanar surface of the first sliding bearing housing; a return bend; anda return leg extending toward the first planar surface of the firstsliding hearing housing, and a foot of the return leg, defining a freeend of the biasing member, presses against the first planar surface ofthe first sliding bearing housing.
 5. The engine of claim 4, whereineach linkage assembly includes a second annular spacer having a secondopening through which the pin extends, the second annular spacerdisposed between the second flange and the first sliding bearing.
 6. Theengine of claim 5, wherein for each linkage assembly the first annularspacer and second annular spacer are contoured to fit against an arcuatesurface of the first sliding bearing.
 7. The engine of claim 6,including a variable area exhaust nozzle, wherein: a flap train of thevariable area exhaust nozzle is the engine movable structure and asynchronization ring for the variable area exhaust nozzle is slidinglydisposed in the engine fixed structure, and each fastener is a bellcrank having three pivotal connection points, including a first pivotalconnection point connected to the first sliding bearing, a secondpivotal connection point that is a fulcrum connected to the engine fixedstructure, and a third pivotal connection point connected to a couplerlink, the coupler link connecting each fastener to the synchronizationring.
 8. The engine of claim 7, wherein for each linkage assembly, thesecond end of the link includes a second sliding bearing in a secondsliding bearing housing, and the second sliding bearing is pivotallyconnected to the flap train.
 9. The engine of claim 8, wherein thesynchronization ring is slidingly disposed in a linearly extendingcavity in the engine fixed structure.
 10. The engine of claim 9, whereinthe flap train includes a plurality of flap train links pivotallyconnected between the flap train and the engine fixed structure forcontrolling pivotal motion of the flap train.